Which of the following phenomena shows the transverse nature of light?

The correct answer is Option (3) → Polarisation

Polarisation means restricting the vibrations of a wave to one direction perpendicular to its motion. This is possible only if the vibrations are transverse to the direction of propagation; in a longitudinal wave the vibrations are along the direction of travel and cannot be selected by a polaroid.

So the fact that light can be polarised shows that light is a transverse wave.

Why the other options are incorrect

• Option (1) Refraction — Incorrect. Refraction occurs for longitudinal waves too (for example, sound bends on entering a region of different temperature).

• Option (2) Diffraction — Incorrect. Diffraction shows the wave nature of light, but sound waves, which are longitudinal, diffract as well.

• Option (4) Interference — Incorrect. Interference shows the wave nature of light, but longitudinal sound waves also interfere (beats, silent points between two speakers).

NCERT (2026-27):
Introduction – “… Finally in Section 10.7 we will discuss the phenomenon of polarisation which is based on the fact that the light waves are transverse electromagnetic waves.”